Recently, electronic devices which can be driven by a battery and be easily carried out, such as tablets and smartphones, have been widespread. Most of these types of devices comprise a microphone and a speaker and can be used as a recorder for recording and playing back sound.
However, at the moment, there is no consideration on visualization of sound at all. Visualization of sound indicates that, for example, when a list of recorded sounds is displayed, the type of each sound is shown to help the user to find out the target sound.